import pygame
from pygame.locals import *
from math import *
surf_scrn = pygame.display.set_mode((200,200))
surf_scrn.fill((255,255,255))
surf_circ = pygame.Surface((100,100))
pygame.draw.circle(surf_circ,(0,30,30),(50,50),50)
N=12; radius=40.0
for i in range(N):
    theta=float(i)/N*pi*2.0; px,py=radius*cos(theta),radius*sin(theta)
    surf_scrn.blit(surf_circ,(100+px-50,100+py-50),special_flags=BLEND_RGB_SUB)
for i in range(N):
    theta=float(i)/N*pi*2.0; px,py=radius*cos(theta),radius*sin(theta)
    pygame.draw.circle(surf_scrn,(0,0,255),(int(100+px+0.5),int(100+py+0.5)),5)
pygame.image.save()
pygame.display.flip()
input()
pygame.quit()